Background: Endotracheal intubation (ETI) is a critical skill for EM physicians. When teaching ETI, supervisors must balance patient safety while maximizing experiential learning. With the advent of video laryngoscopes, learners are often instructed to perform direct laryngoscopy with the video screen only visible to their supervisor. This theoretically allows for real time coaching to maximize first pass success. However, video laryngoscopes have a thicker blade and wider flange than traditional metal blades, which may obstruct a direct non-video assisted glottic view. Our objective was to evaluate the performance of various types of Macintosh blades on simulated ETI metrics.
Methods: This was a cross sectional cohort study of 35 EM physicians (26 residents, 9 attendings) in an urban academic hospital with an ACGME accredited residency program. All physicians performed ETI on a Laerdal® adult airway management trainer with three disposable Macintosh #3 blades (standard metal blade, C-MAC® S video laryngoscope, and Glidescope® MAC S3). ETI metrics included time to successful intubation, number of attempts, and esophageal intubations. Self reported direct glottic view (i.e. no video screen) was reported using a novel metric which assessed both the horizontal and vertical planes (full, partial vertical, partial horizontal, partial vertical and horizontal, and none), as well as traditional Cormack-Lehane classification. This former was done to better assess the impact of the bulk of each blade on glottic view.
Results: Time to intubation (seconds) was significantly shorter with standard metal (Mean 16, 95%CI 13 to 19), compared to C-MAC (34, 95%CI 23 – 45, p=.0017) and Glidescope (37, 95%CI 22 to 51, p=.0129). Glottic view using the novel vertical and horizontal classification system favored standard metal (Chi-squared p=.007). There was trend favoring standard metal using Cormack-Lehane (Chi-squared p=.09). There was no significant difference in number of attempts and esophageal intubations amongst groups
Conclusion: Time to successful intubation was faster, and glottic view improved when using traditional metal Macintosh blades compared to video laryngoscope blades. This should be a consideration for EM trainees choosing their intubation modality when timely first pass success is crucial.